This invention is concerned with a supporting mechanism for supporting mould side portions of three moulds in a glassware forming machine, e.g. of the individual section type.
In glassware forming machines of the individual section type, the supporting mechanisms for the mould side portions comprise two arms each arranged, on the application of a mould closure force thereto, to move in predetermined directions from mould open positions thereof to mould closed positions thereof and to remain in the mould closed positions during a moulding operation of the machine. In some machines of the individual section type, the arms move towards one another arcuately about a common vertical axis to reach their mould closed positions whereas in other machines the arms move linearly towards one another. In the mould closed position, one or more mould side portions (there may be as many as four) supported on each arm cooperate with mould side portions supported on the other arm to define mould cavities in which molten glass can be moulded. On the application of a mould opening force, the arms return to their mould open positions, by moving in the opposite direction to said predetermined direction. In their mould open positions, the mould side portions supported on each arm are separated from those supported on the other arm to allow removal of moulded glass. Such supporting mechanisms are used both for "blank" moulds for moulding gobs of molten glass into parisons, by a pressing or a blowing operation, and also for "finish" moulds for moulding parisons into completed articles of glassware.
Conventionally, the supporting mechanisms comprise an upper and a lower support mounted on each arm. The upper and lower support on an arm cooperate in supporting said one or more mould side portions. The supports are generally mounted on the arm for limited pivoting movements and each defines a recess into which a hook-shaped projection of the mould side portion extends so that the mould side portion hangs on the supports. Normally, a mould side portion rests on the upper support while the lower support prevents the mould side portion from pivoting relative to the upper support. However, with small moulds, there is only one support on each arm on which the mould portion hangs.
In conventional supporting mechanisms where there are three moulds, problems arise due to poor distribution of the mould closure force between the moulds so that one mould may receive excessive or insufficient force. This can result in the formation of pronounced seams on the parison or bottle. Various arrangements for distributing the mould closure force between three moulds are known but have not proved satisfactory. U.S. Pat. No. 3607207 describes a system in which each arm has a double and a single mould side portion support pivotally mounted thereon, the double support on one arm facing half the double support and the single support on the other arm. This system does not achieve equal force distribution. often leaving the centre mould with insufficient force. G.B Patent Specification No. 2132187 describes a system in which one arm has a triple support pivoted thereon while the other arm has two supports which each support one mould portion and cooperate in supporting a mould portion of the centre mould. This system is also not satisfactory as far as the centre mould is concerned. European Patent No. 0059573 describes a system of force balancing levers but is only applicable to linearly-moving moulds.
It is an object of the present invention to provide a simple supporting mechanism for three moulds in which the mould closure force is balanced substantially equally between the three moulds.